But during a changeover early in the second set Cilic appeared to be in trouble.

Cilic, the 2014 US Open winner, began by smashing his racket against a chair in an apparent show of frustration.

Cilic hit his racket against a chair (Getty)

A trainer was then called out with the score at 6-3 3-0 to Federer and during talks the seventh seed began to cry.

It appeared as though he might be about to retire, however he did not receive any notable medical treatment and was able to continue playing.

Cilic talks to a trainer (Getty)

Cilic was clearly struggling (Getty)

Discussions were held before he carried on (Getty)

But despite going on Cilic rapidly went on to lose the second set.

Former Wimbledon champion Boris Becker speculated that the tears may have been due to mental rather than physical suffering.

‘Maybe Cilic is just going through an emotional rollercoaster? That’s what this court does to you. You can’t say you don’t feel good right now, everyone across the world is watching you,’ he told the BBC.

Cilic had slipped earlier in the match – but it wasn’t clear if it was related (Getty)